P-amino substituted tetraphenylthiophenes and electrophotographic photoreceptors containing them

ABSTRACT

There are here provided a novel tetraphenylthiophene derivative represented by the general formula ##STR1## wherein AM is a tertiary amino group, each of l, m and n is the integer 0 or 1 and l≧m≧n are useful as the charge-transporting material in an electrophotographic photoreceptor having an electrically conductive base and a photosensitive layer thereon containing a charge-transporting material and a charge-generating material, which preferably is an azo compound.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to novel p-amino substitutedtetraphenylthiophenes and to electrophotographic photoreceptorscontaining them. More specifically, it relates to an electrophotographicphotoreceptor in which a novel p-amino substituted tetraphenylthiopheneis contained as a charge-transporting material in a photosensitive layeron an electrically conductive base.

(2) Description of the Prior Art

Heretofore, inorganic photosensitive materials such as selenium, cadmiumsulfide and zinc oxide have been widely used as photosensitive materialsfor electrophotographic photoreceptors. However, the photoreceptorsusing such photosensitive materials do not sufficiently satisfy therequirements for electrophotographic photoreceptors such as sensitivity,light stability, moisture-proofness and durability. For example, thephotoreceptors using selenium materials have excellent sensitivity butare susceptible to crystallization due to heat or contaminants, so thatthe characteristics of the photoreceptors deteriorate with use. Inaddition, this type of photoreceptors has many drawbacks, viz.,manufacturing cost is high because of the utilization of vacuumevaporation and it is difficult to mold them into the form of a beltbecause of poor flexibility. The photoreceptors using the cadmiumsulfide material have poor moisture-proofness and durability.Furthermore, the photoreceptors in which zinc oxide is used haveunsatisfactory durability.

In order to eliminate these disadvantages of the photoreceptors usingthe inorganic photosensitive materials, various photoreceptors based onorganic photosensitive materials have been investigated.

The photoreceptors developed to remove the above-mentioned drawbacksinclude function-separated photoreceptors in which a charge-generatingfunction and a charge-transporting function are separately allocated todifferent materials. In the function-separated photoreceptors, materialshaving various desirable functions can be selected from a wide range ofmaterials and combined with one another, which permits preparingphotoreceptors having high sensitivity and sufficient durability.

Requirements for the charge-transporting material contained in theelectrophotographic photoreceptor are as follows:

(1) Possess sufficiently high ability to receive electric chargesgenerated from the charge-generating material.

(2) Capable of promptly transporting the received charges.

(3) Capable of successfully transporting the charges even in lowelectric field so that no charges remain.

In addition, the photoreceptor must be stable to light and heat duringthe repeating operation of electrification, exposure, development andtransfer, and must have enough durability to obtain faithfullyreproduced copy images.

As the charge-transporting materials, various compounds have beenreported. For example, poly(N-vinylcarbazole) has been known for sometime as a light-conductive material and photoreceptors in which thiscompound is used as the charge-transporting material have been put intopractice. However, this type of photoreceptors has poor flexibility andis brittle, with the result that they readily crack. This fact meansthat their durability is so poor as to not withstand repeated use.Furthermore, when their flexibility is improved by the use of a binder,electrophotographic properties deteriorate.

Because low-molecular weight compounds have no coating properties, whena photosensitive layer is formed therewith, such a compound is mixedgenerally with a binder in an arbitrary ratio. Many charge-transportingmaterials have been suggested which comprise low-molecular weightcompounds. For example, hydrazone compounds have high sensitivity as thecharge-transporting material. (See Japanese Patent Publication Laid-openNos. 55-46761, 55-52064, 57-58156 and 57-58157). However, thesecompounds tend to decompose by ozone generated during corona dischargeand they are unstable to light and heat. In addition, when this kind ofcharge-transporting material is used, the thus-obtained images are poorin contrast or are fogged, owing to the degradation of charge retentionability by repeated use or owing to the accumulation of residualpotential, even when initial performance is good.

Many other charge-transforming materials have been suggested but none ofthem sufficiently satisfy the practical requirements for use in anelectrophotographic photoreceptor. Therefore, the development of betterphotoreceptors is desired.

OBJECTS OF THE INVENTION

An object of the present invention is to provide novel compounds whichare useful as a charge-transporting material.

Another object of the present invention is to provide anelectrophotographic photoreceptor having adequate sensitivity andexcellent durability.

These and other objects of the present invention can be achieved by theuse of a p-tert.-amino substituted tetraphenylthiophene as thecharge-transporting agent in an electrophotographic photoreceptor.

SUMMARY OF THE INVENTION

The p-tert.-amino-substituted tetraphenylthiophenes of this inventioncan be represented by the general formula ##STR2## wherein each AM is atertiary amino group, preferably of the formula --NR₁ R₂ wherein each ofR₁ and R₂ is an alkyl group, an aralkyl group or an aryl group or R₁ andR₂ together with the nitrogen atom form a heterocyclic amino group, eachof l, m and n is the integer 0 or 1 and l≧m≧n.

The electrophotographic photoreceptors of this invention comprise anelectrically conductive base and a photosensitive layer thereoncontaining a tetraphenylthiophene of the general formula (I) as a

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are cross-sectional views illustrating constitutionalexamples of electrophotographic photoreceptors.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the p-tert.-amino substituted tetraphenylthiophenes of generalformula (I), examples of R₁ and R₂ are those of 1 to 8 carbon atoms,which may be straight or branched chain, e.g., lower alkyl such asmethyl, ethyl, isopropyl, butyl and octyl; examples of R₁ and R₂ aralkylgroups are carbocyclic aryl of 7 to 10 carbon atoms and 1 to 4 carbonatoms in the alkyl moiety, such as benzyl and phenethyl: and examples ofR₁ and R₂ aryl groups are carbocyclic aryl of 6 carbon atoms, e.g.,phenyl, naphthyl and biphenyl.

The R₁ and R₂ groups can be alike or different and one or more of themmay bear one or more, e.g., 1, 2 or 3 simple substituents. Examples ofsubstituents which can be present on an R₁ or R₂ group are halogenatoms, e.g., chlorine and bromine; hydrocarbon groups of 1 to 12 carbonatoms, including alkyl of 1 to 8 carbon atoms, e.g., lower alkyl such asmethyl, ethyl, butyl and octyl, aralkyl groups of 7 to 10 carbon atoms,such as benzyl and phenethyl, and aryl groups, such as phenyl, biphenyland naphthyl; an ether group including alkoxy groups of 1 to 5 carbonatoms, e.g., lower alkoxy such as methoxy, ethoxy, and butoxy; and anester group including carboxylate groups of 1 to 6 carbon atoms, e.g.,carbo-lower alkoxy, such as carbomethoxy and carboethoxy.

Examples of tertiary amino groups in which R₁ and R₂ are linked with theamino nitrogen atom to form a cycloalkyl amine include a pyrrolidinogroup and a piperidino group.

In the compounds of formula (1), preferably R₁ and R₂ both are arylgroups, since these compounds have high sensitivity and have excellentsolubility in organic solvents.

The compounds represented by the above-mentioned general formula (I) canbe synthesized, for example, by the following procedures:

(1) Reacting an amino compound represented by the general formula (V)##STR3##

wherein each of l, m and n is the integer 0 to 1 l≧m≧n, with an alkylpara-toluenesulfonate, dialkyl sulfate, and alcohol, an alkyl halide,aryl halide or like reagent reactive with a primary group. (2) Reactinga compound represented by the general formula (VI) ##STR4## where ineach of 1, m and n is the integer 0 or 1 and 1≧m≧n, and X is a halogenatom, preferably an iodine atom, with an amine represented by thegeneral formula (VII) ##STR5## wherein R₁ and R₂ are as defined above.

Typical examples of compounds which can be used in the present inventionare those recited in Table 1, which examples are illustrative and notrestrictive.

                                      TABLE 1                                     __________________________________________________________________________     ##STR6##                                                                     Compound No.                                                                          l  m  n  R.sub.1      R.sub.2                                         __________________________________________________________________________    1       0  0  0                                                                                 ##STR7##                                                                                   ##STR8##                                       2       0  0  0                                                                                 ##STR9##                                                                                   ##STR10##                                      3       0  0  0                                                                                 ##STR11##                                                                                  ##STR12##                                      4       0  0  0                                                                                 ##STR13##                                                                                  ##STR14##                                      5       0  0  0                                                                                 ##STR15##                                                                                  ##STR16##                                      6       0  0  0                                                                                 ##STR17##                                                                                  ##STR18##                                      7       1  0  0                                                                                 ##STR19##                                                                                  ##STR20##                                      8       1  0  0                                                                                 ##STR21##                                                                                  ##STR22##                                      9       1  0  0                                                                                 ##STR23##                                                                                  ##STR24##                                      10      1  0  0                                                                                 ##STR25##                                                                                  ##STR26##                                      11      1  0  0                                                                                 ##STR27##                                                                                  ##STR28##                                      12      1  0  0                                                                                 ##STR29##                                                                                  ##STR30##                                      13      1  0  0                                                                                 ##STR31##                                                                                  ##STR32##                                      14      1  0  0                                                                                 ##STR33##                                                                                  ##STR34##                                      15      1  0  0                                                                                 ##STR35##                                                                                  ##STR36##                                      16      1  0  0                                                                                 ##STR37##                                                                                  ##STR38##                                      17      1  0  0                                                                                 ##STR39##                                                                                  ##STR40##                                      18      1  0  0                                                                                 ##STR41##                                                                                  ##STR42##                                      19      1  0  0                                                                                 ##STR43##                                                                                  ##STR44##                                      20      1  1  0                                                                                 ##STR45##                                                                                  ##STR46##                                      21      1  1  0                                                                                 ##STR47##                                                                                  ##STR48##                                      22      1  1  0                                                                                 ##STR49##                                                                                  ##STR50##                                      23      1  1  0                                                                                 ##STR51##                                                                                  ##STR52##                                      24      1  1  0                                                                                 ##STR53##                                                                                  ##STR54##                                      25      1  1  0                                                                                 ##STR55##                                                                                  ##STR56##                                      26      1  1  1                                                                                 ##STR57##                                                                                  ##STR58##                                      27      1  1  1                                                                                 ##STR59##                                                                                  ##STR60##                                      28      1  1  1                                                                                 ##STR61##                                                                                  ##STR62##                                      29      1  1  1                                                                                 ##STR63##                                                                                  ##STR64##                                      30      1  1  1                                                                                 ##STR65##                                                                                  ##STR66##                                      31      1  1  1                                                                                 ##STR67##                                                                                  ##STR68##                                      __________________________________________________________________________

A compound of the present invention, when used as a charge-transportingmaterial in an electrophotographic photoreceptor, is combined with acharge-generating material.

Any material can be used as the charge-generating material, so long asit has an ability to generate an electric charge. Typical examples ofcharge-generating materials include inorganic materials such asselenium, selenium alloys, amorphous silicon and cadmium sulfide; andorganic dyes and pigments of phthalocyanine, perylene, perynone, indigo,anthraquinone, cyanine, azo compounds, and the like. The phthalocyanineand azo compounds are especially suitable for the use as thecharge-generating materials in combination with a charge-transportingmaterial of the present invention.

Of the azo compound charge-generating materials which can impart to theelectrophotographic photoreceptor excellent characteristics whenemployed in combination with a charge-transporting material of thepresent invention, compounds represented by one of the followingformulae (II), (III) and (IV) are particularly preferred: ##STR69##wherein A is a coupler residuum, ##STR70## wherein A is a couplerresiduum, and ##STR71## wherein A is a coupler residuum.

The reason why a combination of one of these compounds and acharge-transporting material of this invention is particularly desirablecould be due to various factors, but the advantages of the combinationcould not be predicted, based on the present technical level in thisfield. Therefore, the advantageous combination of a charge-transportingmaterial of the present invention and an azo compound charge-generatingmaterial of formula (II), (III) or (IV) is also a surprising discovery.

Examples of the coupler residuum represented by the group A in thegeneral formulae (II), (III) and (IV) include the following residua (a)to (d):

(a) Coupler residua having the general formula (VIII) ##STR72## whereinX is a divalent bridging group which, with the benzene ring bearing the-OH and Y groups, forms a fused polycyclic carbocyclic or heterocyclicring and Y is --ON(R₄)--R_(b) 3 or --CONH.N=C(R₆)-R₅ wherein R3 is ahydrocarbon or a heterocyclic ring group, R₄ is a hydrogen atom, analkyl group or a phenyl group, or R₃ and R₄ collectively with thenitrogen atom to which they are linked form a heterocyclic ring. R₅ is ahydrocarbon ring group, a heterocyclic ring group or a styryl group, R₆is a hydrogen atom, an alkyl group or a phenyl group, or R₅ and R₆collectively with the carbon atoms to which they are linked form a ring.Like R₁ and R₂, the X, R₃, R₄, R₅ and/or R₆ groups can have one or moresimple substituents thereon.

Typical examples of rings formed by X in the general formula (VIII)include hydrocarbon rings such as naphthalene and anthracene,heterocyclic rings such as indole, carbazole, benzocarbazole anddibenzofuran, which are each condensed with the benzene ring bearing ahydroxyl group and Y.

When X bears a substituent, examples thereof include halogen atoms, suchas chlorine and bromine, a hydroxyl group.

Examples of the cyclic R₃ and R₅ groups include carbocyclic rings suchas phenyl, naphthyl, anthryl and pyrenyl; and heterocyclic rings such aspyridyl, thienyl, furyl, indolyl, benzofuranyl, carbazolyl anddibenzofuranyl. An example of a ring which can be formed collectively byR5 and R₆ is a fluorene ring.

When an R₃ or R₅ bears a substituent, examples thereof include alkylgroups such as methyl, ethyl butyl, alkoxy groups such as methoxy,ethoxy, propoxy and butoxy, halogen atoms such as chlorine and bromine,a halomethyl group such as trifluoromethyl, dialkylamino groups such asdimethylamino and diethylamino, nitro, cyano, carboxyl and esters, e.g.,alkyl such as methyl and ethyl, thereof.

When R₄ or R₆ is a phenyl group, it also can bear a substituent, e.g., ahalogen atom such as chlorine or bromine.

(b) Coupler residua having general formula (IX) and (X) ##STR73##wherein R₇ is a hydrocarbon group, which may be substituted.

Examples of R₇ include alkyl groups as defined above for R₁ and R₂,methyl, ethyl propyl, butyl and octyl and alkoxyalkyl groups, such as amethoxyethyl and an ethoxyethyl.

(c) Coupler residues having general formula (XI) ##STR74## wherein R₈ isan alkyl group, a carbamoyl group, a carboxy group or its ester, and R₉is a carbocyclic ring group which may be substituted.

Examples of R₉ include hydrocarbon ring groups such as phenyl andnaphthyl. Examples of substituents on the R₉ group are alkyl groups,such as methyl, ethyl, propyl and butyl, alkoxy groups, such as methoxy,ethoxy, propoxy, and butoxy, dialkylamino groups, such as a diethylaminoand diethylamino, halogen atoms, such as chlorine and bromine, a nitrogroup and a cyano group.

(d) Coupler residues having general formula (XII) and (XIII) ##STR75##Wherein Z is a divalent hydrocarbon or heterocyclic ring groups, each ofwhich may be substituted and which with the nitrogen atoms form aheterocyclic ring system.

Typical examples of Z include a divalent monocyclic aromatic hydrocarbongroup such as o-phenylene, condensed polycyclic aromatic hydrocarbongroups, such as an o-naphthylene, peri-naphthylene,1,2-anthraquinonylene and 9,10-phenanthrylene, and divalent heterocyclicring groups, such as 3,4-pyrazoldiyl, 2,3-pyridinediyl,4,5-pyrimidinediyl, 6,7-imidazolediyl, 5,6-benzimidazolediyl and6,7-quinolinediyl. Examples of Z ring group substituents include alkylgroups, such as methyl, ethyl, propyl and butyl, alkoxy groups, such asmethoxy, ethoxy, propoxy and butoxy, dialkylamino groups, such asdimethylamino and diethylamino, halogen atoms such as chlorine andbromine, a nitro group and a cyano group.

Of the coupler residua above recited, those which are represented by thegeneral formula (VIII) are most preferable because they producecharge-generating azo compounds with high photosensitive properties andtheir intermediate raw materials are so readily available that the canbe manufactured at low cost.

Typical examples of the coupler residues are as follows: ##STR76##

The azo compounds represented by the general formula (II), (III) and(IV) can be manufactured by, for example, a method disclosed in EP No.0270685.

The compound of the present invention has no ability to provide coatingfilms by itself, and therefore it is used together with a binder inorder to form a photosensitive layer. As the binder, an insulatingpolymer can be employed. Examples of the insulating polymer includepolystyrene, polyacrylamide, polyvinyl chloride, polyester resins,polycarbonate resins, epoxy resins, phenoxy resins and polyamide resins.In particular, the polyester resins and polycarbonate resins can besuitably used. In addition, poly-N-vinylcarbazole which hascharge-transporting ability by itself can be also employed.

The photoreceptor may be in the form of a constitution in which aphotosensitive layer 4 containing a charge-generating material 2 and acharge-transporting material 3 is superposed upon an electricallyconductive base 1, as shown in FIG. 1; a constitution in which aphotosensitive layer 4' is superposed upon the electrically conductivebase 1, the photosensitive layer 4' being composed of acharge-generating layer 6 containing the charge-generating material 2and a charge-transporting layer 5 containing the charge transportingmaterial 3 thereon, as shown in FIG. 2; and a constitution in which thecharge-generating layer 6 and the charge-transporting layer 5 in FIG. 2are inversely disposed. The photoreceptor having any one of theabove-mentioned constitutions is effective in the present invention, butthe laminate type photoreceptor shown in FIG. 2 is preferable in thatexcellent electrophotographic characteristics can be obtained.

The constitution of the photoreceptor will be further described indetail in reference to FIG. 2.

Examples of usable raw materials for the electrically conductive base 1include metallic plates of aluminum, copper and zinc; those which havebeen prepared by depositing conductive materials such as aluminum andSnO₂ on plastic sheets or films of polyester and the like; and papers orresins which have been rendered conductive.

The charge-generating layer 6 can be formed from the above-mentionedcharge-generating material 2 in accordance with a method ofvacuum-evaporating the charge-generating material 2 on the electricallyconductive base 1, a method of applying and drying a solution containingthe charge-generating material 2, a method of applying and drying adispersion in which fine particles of the charge-generating material 2are dispersed, or another method.

The thickness of the charge-generating layer 6 is in the range of 0.01to 5 μm, preferably 0.05 to 2 μm. When this thickness is less than 0.01μm, the generation of the charge is insufficient, and when it is morethan 5 μm, residual potential is high, which is practicallyunpreferable.

The charge-transporting layer 5 may be formed by dissolving the compoundof the present invention and the above-mentioned binder in a suitablesolvent, and then applying and drying the mixture. In thecharge-transporting layer 5, the charge-transporting material 3 iscontained in an amount of 10 to 95% by weight, preferably 30 to 90% byweight. When the charge-transporting material 3 is less than 10% byweight, the charge is scarcely transported, and when it is more than 95%by weight, mechanical strength of the photoreceptor is poor, which ispractically unpreferable.

The thickness of the charge-transporting layer 5 is preferably in therange of 3 to 50 μm, more preferably 5 to 30 μm. When this thickness isless than 3 μm, electrification quantity is insufficient, and when it ismore than 50 μm, residual potential is high, which is practicallyunpreferable.

Between the photosensitive layer and the electrically conductive base,an intermediate layer may be interposed. Suitable examples of rawmaterials for the intermediate layer include polyamide, nitrocellulose,casein and polyvinyl alcohol, and the thickness of the intermediatelayer is preferably 1 μm or less.

As described above, the electrophotographic photoreceptor of the presentinvention may be composed of the compound represented by the generalformula (I), the electrically conductive base, the charge-generatingmaterial and the binder, but other constitutional elements of thephotoreceptor may be additionally used, so long as they have functionsas such elements.

In the electrophotographic photoreceptor of the present invention, anovel compound represented by the general formula (I) is used as thecharge-transporting material, and therefore this photoreceptor has highsensitivity, sufficient durability to repeating use, and other excellentadvantages.

Now, the present invention will be described in detail by way ofexamples, but the scope of the present invention should not be limitedto these examples.

PREPARATION EXAMPLE 1 (Synthesis of Exemplary Compound No. 7)

In 50 ml of sulfolane were dispersed 12 g of2,5-bis(4-iodophenyl)-3,4-diphenylthiophene, 10 g ofN-phenyl-2naphthylamine, 10 g of anhydrous potassium carbonate and 8 gof electrolytic copper, and the mixture was then stirred at 190° C. for40 hours. After standing, the mixture was added to 100 ml of water, andthe resultant precipitate was collected by filtration and was thenwashed with water and methanol in this order, followed by drying. Thethus obtained crude product was extracted with benzene, and the extractwas purified through a silica gel column chromatography using a mixedsolvent of benzene and hexane (1:1) as a developing solution. Byrecrystallization from a mixed solvent of benzene and acetonitrile, 15 gof light-yellow crystals (melting point=145° to 146° C.) was obtained.

It was confirmed by elemental analysis that the product was ExemplaryCompound No. 7.

    ______________________________________                                        Results of Elemental Analysis (%)                                                      C    H           N      S                                            ______________________________________                                        Calcd.     87.56  5.14        3.40 3.90                                       Found      87.34  5.08        3.31 4.04                                       ______________________________________                                    

PREPARATION EXAMPLE 2 (Synthesis of Exemplary Compound No. 3)

In 200 ml of orthodichlorobenzene (hereinafter referred to simply asODCB) was dissolved 4.1 g of 2-(4-aminophenyl)3,4,5-triphenylthiophene,and to the mixture were added 5.1 g of iodobenzene, 11 g of anhydrouspotassium carbonate, 2.6 g of electrolytic copper and 0.6 g of18-crown-6-ether. In a nitrogen atmosphere, the mixture was then heatedunder reflux with vigorous stirring for 48 hours. A solid was collectedby filtration, and afterward ODCB was distilled off from the reactionsolution by means of steam distillation. The thus obtained residue waspurified through a silica gel column chromatograph using benzene as adeveloping solution. Afterward, by recrystallization from a mixedsolvent of benzene and hexane (1:1), 2.5 g of light-yellow crystals(melting point=225.0° to 228.8° C.) was obtained.

It was confirmed by elemental analysis that the product was ExemplaryCompound No. 3.

    ______________________________________                                        Results of Elemental Analysis (%)                                                      C    H           N      S                                            ______________________________________                                        Calcd.     86.45  5.26        2.52 5.77                                       Found      86.15  5.00        2.80 6.05                                       ______________________________________                                    

PREPARATION EXAMPLE 3 (Synthesis of Exemplary Compound No. 4)

The same procedure as in Preparation Example 2 was conducted with theexception that 4.1 g of 2-(4-amino-phenyl)-3,4,5-triphenylthiophene and8.2 g of p-iodoanisole were used, to obtain 3 g of yellow crystals(melting point=132.8° to 134.6° C.).

It was then confirmed by elemental analysis that the product wasExemplary Compound No. 4.

    ______________________________________                                        Results of Elemental Analysis (%)                                                      C    H           N      S                                            ______________________________________                                        Calcd.     81.92  5.40        2.27 5.20                                       Found      81.90  5.19        2.16 4.91                                       ______________________________________                                    

PREPARATION EXAMPLE 4 (Synthesis of Exemplary Compound No. 8)

The same procedure as in Preparation Example 2 was conducted with theexception that 4.2 g of 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene and12.5 g of iodobenzene were used, to obtain 4 g of light-yellow crystals[melting point=126° to 129° C.; λmax=370 nm (CHCl₃)].

It was then confirmed by elemental analysis that the product wasExemplary Compound No. 8.

    ______________________________________                                        Results of Elemental Analysis (%)                                                      C    H           N      S                                            ______________________________________                                        Calcd.     86.39  5.30        3.88 4.43                                       Found      86.29  4.94        3.85 4.18                                       ______________________________________                                    

PREPARATION EXAMPLE 5 (Synthesis of Exemplary Compound No. 10)

The same procedure as in Preparation Example 2 was conducted with theexception that 4.2 g of 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene and13.2 g of p-iodotoluene were used, to obtain 4 g of yellow crystals(melting point=241.4° to 243.3° C.). It was then confirmed by elementalanalysis that the product was Exemplary Compound No. 10.

    ______________________________________                                        Results of Elemental Analysis (%)                                                      C    H           N      S                                            ______________________________________                                        Calcd.     86.34  5.95        3.60 4.12                                       Found      86.30  5.93        3.52 4.10                                       ______________________________________                                    

PREPARATION EXAMPLE 6 (Synthesis of Exemplary Compound No. 21)

The same procedure as in Preparation Example 2 was conducted with theexception that 4.3 g of 2,3,5-tris(4-aminophenyl)-4-phenylthiophene and18.5 g of iodobenzene were used, to obtain 4 g of yellow crystals[melting point=238° C.; to 242° C.; λmax=373 nm (CHCl₃)].

It was then confirmed by elemental analysis and from a molecular ionpeak at 889(M+) in FD-MASS that the product was Exemplary Compound No.21.

    ______________________________________                                        Results of Elemental Analysis (%)                                                      C    H           N      S                                            ______________________________________                                        Calcd.     86.36  5.32        4.72 3.60                                       Found      86.82  5.22        4.52 3.38                                       ______________________________________                                    

PREPARATION EXAMPLE 7 (Synthesis of Exemplary Compound No. 27)

The same procedure as in Preparation Example 2 was conducted with theexception that 4.3 g of tetrakis(4-aminophenyl)thiophene and 24.5 g ofiodobenzene were used, to obtain 6 g of yellow crystals [meltingpoint=228° to 232° C.; λmax=375 nm (CHCl₃)].

It was then confirmed by elemental analysis and from a molecular ionpeak at 889(M+) in FD-MASS that the product was Exemplary Compound No.27.

    ______________________________________                                        Results of Elemental Analysis (%)                                                      C    H           N      S                                            ______________________________________                                        Calcd.     86.33  5.34        5.30 3.03                                       Found      86.62  5.08        5.04 2.89                                       ______________________________________                                    

EXAMPLE 1

In a ball mill, 0.5 g of polyester resin (made by Toyobo Co., Ltd.;trade name "Bylon 200"), 0.5 g of a diazo dye (CG-1) represented by thestructural formula ##STR77## p wherein A is a group having the formula##STR78## and Ph is a phenyl group, and 50 g of tetrahydrofuran wereground and mixed, and an aluminum plate was coated with the obtaineddispersion by the use of a wire bar. Afterward, the coated plate wasdried at 80° C. for 20 minutes to form a charge-generating layer havinga thickness of about 0.5 μm.

This charge-generating layer was then coated by the use of a wire barwith a solution in which 1 g of Exemplary Compound No. 8, 1 g ofpolyester resin (trade name "Bylon 200"; made by Toyobo Co., Ltd.) weredissolved in 10 g of chloroform. The layer was afterward dried at 80° C.for 30 minutes to form a charge-transporting layer thereon having athickness of about 18 μm, thereby preparing a laminate typephotoreceptor as shown in FIG. 2.

The photoreceptor was electrified by corona discharge of 6 KV from anelectrostatic copy paper test device (made by Kawaguchi Denki SeisakujoCo., Ltd.; model EPA-No. 8100), and at this time, surface potential VOwas measured. Afterward, the photoreceptor was allowed to stand in adark place for 2 seconds, and at this time, a surface potential V₂ wasmeasured. In succession, the specimen was irradiated with light from ahalogen lamp (color temperature=2,856° K.) so that the surfaceilluminance of the photoreceptor might be 5 lux, and a period of timewhich was taken until the surface potential attained a level of 1/2 ofV₂ was measured. From measurements, the value of a half-life exposureE_(1/2) (lux·sec) was then calculated. Furthermore, after 10 secondswere elapsed from the start of the light irradiation, a surfacepotential V₁₂, i.e., a residual potential was measured. Afterward, theoperation of an electrification and an exposure were repeated 1,000times.

EXAMPLES 2 to 6

The same procedure as in Example 1 was repeated with the exception thatcharge-transporting materials were changed to prepare photoreceptors,and measurements were done for the same items. The usedcharge-transporting materials and the measured results are set forth inTable 2.

EXAMPLE 7

The same procedure as in Example 1 was conducted with the exception thata diazo dye (CG-2) represented by the following structural formula wasused as a charge-generating material to prepare a photoreceptor, andmeasurements were done for the same items: ##STR79## wherein B is agroup having the formula: ##STR80##

EXAMPLES 8 to 12

The same procedure as in Example 2 was conducted with the exception thatthe charge-transporting material was changed to prepare photoreceptors,and measurements were then made for the same items. The usedcharge-transporting materials and the measured results are set forth inTable 2.

EXAMPLE 13

The same procedure as in Example 1 was conducted with the exception thata disazo dye (CG-3) represented by the structural formula ##STR81##wherein B is a group having the formula ##STR82## was employed as acharge-generating material to prepare a photoreceptor, and measurementswere then made for the same items.

EXAMPLE 14

The same procedure as in Example 1 was conducted with the exception thatτ-phthalocyanine (CG-4) was used as a charge-generating material, toprepare a photoreceptor, and measurements were then made for the sameitems.

EXAMPLES 15 to 90

Following the manner of Example 1 with the exception that othercharge-generating materials and charge-transporting materials were used,photoreceptors were prepared, and measurements were then made. Ascharge-generating materials, there were used azo compounds representedby the general formulae (II), (III) and (IV). Combinations of the usedcharge-generating materials and charge-transporting materials are setforth in Table 2. In this table, the used charge-generating materialsare shown by symbols of the general formulae and the above-mentionedcouplers.

COMPARATIVE EXAMPLE 1

The same procedure as in Example 1 was conducted with the exception thatdisazo dye (CG-3) represented by the structural formula ##STR83##wherein B is a group having the formula ##STR84## was used as acharge-generating material and2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole (CT-1) was used as acharge-transporting material, to prepare a photoreceptor, and theoperation of electrification exposure was repeated 1,000 times.

The measured results of Examples 1 to 90 and Comparative Example 1 areset forth in Table 2.

                                      TABLE 2                                     __________________________________________________________________________           Charge-                                                                            Charge-                                                                  Generat-                                                                           Trans-                                                                              Number of                                                          ing  porting                                                                             Repeated          E.sub.1/2                                 Example                                                                              Material                                                                           Material                                                                            Operation                                                                           V.sub.0 (V)                                                                       V.sub.2 (V)                                                                       V.sub.12 (V)                                                                      (lux · sec)                      __________________________________________________________________________    Example 1                                                                            CG-1 Compound                                                                            1     -1120                                                                             -1080                                                                             0   1.2                                                   No. 8 1000  -1060                                                                             -1010                                                                             0   1.3                                       Example 2                                                                            "    Compound                                                                            1     -1004                                                                             -980                                                                              0   2.0                                                   No. 7 1000  -990                                                                              -970                                                                              -1  2.0                                       Example 3                                                                            "    Compound                                                                            1     -1210                                                                             -1130                                                                             -1  2.2                                                   No. 3 1000  -1220                                                                             -1120                                                                             -2  2.6                                       Example 4                                                                            "    Compound                                                                            1     -990                                                                              -940                                                                              -1  2.0                                                   No. 14                                                                              1000  -940                                                                              -900                                                                              -1  2.8                                       Example 5                                                                            "    Compound                                                                            1     -1310                                                                             -1270                                                                             0   3.6                                                   No. 21                                                                              1000  -1290                                                                             -1200                                                                             0   4.2                                       Example 6                                                                            "    Compound                                                                            1     -1230                                                                             -1150                                                                             -1  2.8                                                   No. 27                                                                              1000  -1220                                                                             -1130                                                                             -1  3.1                                       Example 7                                                                            CG-2 Compound                                                                            1     -980                                                                              -965                                                                              0   2.0                                                   No. 8 1000  -970                                                                              -950                                                                              0   2.4                                       Example 8                                                                            "    Compound                                                                            1     -980                                                                              -950                                                                              0   2.3                                                   No. 7 1000  -970                                                                              -945                                                                              0   2.4                                       Example 9                                                                            "    Compound                                                                            1     -995                                                                              -960                                                                              -2  2.4                                                   No. 3 1000  -940                                                                              -925                                                                              -2  3.1                                       Example 10                                                                           "    Compound                                                                            1     -1130                                                                             -1065                                                                             0   2.1                                                   No. 14                                                                              1000  -1085                                                                             -1000                                                                             0   2.2                                       Example 11                                                                           "    Compound                                                                            1     -1015                                                                             -980                                                                              -1  1.8                                                   No. 21                                                                              1000  -975                                                                              -940                                                                              -2  1.9                                       Example 12                                                                           "    Compound                                                                            1     -1130                                                                             -1065                                                                             0   3.2                                                   No. 27                                                                              1000  -1080                                                                             -1010                                                                             -2  4.9                                       Example 13                                                                           CG-3 Compound                                                                            1     -815                                                                              -795                                                                              -1  1.8                                                   No. 8 1000  -810                                                                              -770                                                                              -2  2.1                                       Example 14                                                                           CG-4 Compound                                                                            1     -855                                                                              -820                                                                              -3  2.3                                                   No. 8 1000  -840                                                                              -800                                                                              -3  2.6                                       Example 15                                                                           (II)-                                                                              Compound                                                                            1     -1105                                                                             -950                                                                              0   2.5                                              (A-1)                                                                              No. 7 1000  -1110                                                                             -940                                                                              -1  2.5                                       Example 16                                                                           (II)-                                                                              Compound                                                                            1     -1170                                                                             -1100                                                                             -1  2.1                                              (A-1)                                                                              No. 8 1000  -1115                                                                             -1060                                                                             -1  2.5                                       Example 17                                                                           (II)-                                                                              Compound                                                                            1     -1150                                                                             -1090                                                                             0   2.4                                              (A-1)                                                                              No. 24                                                                              1000  -1100                                                                             -1060                                                                             0   3.1                                       Example 18                                                                           (II)-                                                                              Compound                                                                            1     -1220                                                                             -1170                                                                             -2  3.4                                              (A-1)                                                                              No. 30                                                                              1000  -1150                                                                             -1100                                                                             -5  3.9                                       Example 19                                                                           (II)-                                                                              Compound                                                                            1     -990                                                                              -940                                                                              -1  2.2                                              (A-9)                                                                              No. 7 1000  -980                                                                              -935                                                                              -1  2.2                                       Example 20                                                                           (II)-                                                                              Compound                                                                            1     -1150                                                                             -1070                                                                             0   2.3                                              (A-9)                                                                              No. 8 1000  -1110                                                                             -1020                                                                             -1  3.8                                       Example 21                                                                           (II)-                                                                              Compound                                                                            1     -1170                                                                             -1110                                                                             -1  2.8                                              (A-9)                                                                              No. 24                                                                              1000  -1100                                                                             -1050                                                                             -3  3.6                                       Example 22                                                                           (II)-                                                                              Compound                                                                            1     -1150                                                                             -1070                                                                             -2  3.6                                              (A-9)                                                                              No. 30                                                                              1000  -1095                                                                             -1030                                                                             -3  4.4                                       Example 23                                                                           (II)-                                                                              Compound                                                                            1     -1010                                                                             -980                                                                              -1  2.5                                              (A-21)                                                                             No. 7 1000  -1000                                                                             -980                                                                              -1  2.7                                       Example 24                                                                           (II)-                                                                              Compound                                                                            1     -1190                                                                             -1120                                                                             0   2.0                                              (A-21)                                                                             No. 8 1000  -1120                                                                             -1050                                                                             0   2.6                                       Example 25                                                                           (II)-                                                                              Compound                                                                            1     -1220                                                                             -1150                                                                             0   3.6                                              (A-21)                                                                             No. 24                                                                              1000  -1140                                                                             -1060                                                                             -2  4.4                                       Example 26                                                                           (II)-                                                                              Compound                                                                            1     -1270                                                                             -1200                                                                             -1  3.2                                              (A-21)                                                                             No. 30                                                                              1000  -1180                                                                             -1100                                                                             -3  3.9                                       Example 27                                                                           (II)-                                                                              Compound                                                                            1     -1140                                                                             -1010                                                                             0   2.1                                              (A-49)                                                                             No. 7 1000  -1150                                                                             -1000                                                                             -1  2.2                                       Example 28                                                                           (II)-                                                                              Compound                                                                            1     -1210                                                                             -1140                                                                             0   2.2                                              (A-49)                                                                             No. 8 1000  -1160                                                                             -1110                                                                             -1  2.6                                       Example 29                                                                           (II)-                                                                              Compound                                                                            1     -1220                                                                             -1145                                                                             -3  3.1                                              (A-49)                                                                             No. 24                                                                              1000  -1170                                                                             -1090                                                                             -5  3.8                                       Example 30                                                                           (II)-                                                                              Compound                                                                            1     -1070                                                                             -1015                                                                             -1  2.4                                              (A-49)                                                                             No. 30                                                                              1000  -1020-                                                                            -960                                                                              -2  3.5                                       Example 31                                                                           (II)-                                                                              Compound                                                                            1     -980                                                                              -970                                                                              0   2.5                                              (A-120)                                                                            No. 7 1000  -985                                                                              -975                                                                              0   2.5                                       Example 32                                                                           (II)-                                                                              Compound                                                                            1     - 1110                                                                            -1050                                                                             -1  2.2                                              (A-120)                                                                            No. 8 1000  -1080                                                                             -1040                                                                             -2  2.6                                       Example 33                                                                           (II)-                                                                              Compound                                                                            1     -1220                                                                             -1140                                                                             -3  3.4                                              (A-120)                                                                            No. 24                                                                              1000  -1120                                                                             -1040                                                                             -5  4.2                                       Example 34                                                                           (II)-                                                                              Compound                                                                            1     -1230                                                                             -1110                                                                             0   2.6                                              (A-120)                                                                            No. 30                                                                              1000  -1150                                                                             -1050                                                                             -1  3.6                                       Example 35                                                                           (III)-                                                                             Compound                                                                            1     -1220                                                                             -1150                                                                             0   2.0                                              (A-1)                                                                              No. 7 1000  -1240                                                                             -1170                                                                             0   2.0                                       Example 36                                                                           (III)-                                                                             Compound                                                                            1     -1110                                                                             -1060                                                                             -2  2.4                                              (A-1)                                                                              No. 8 1000  -1070                                                                             -1010                                                                             -3  2.9                                       Example 37                                                                           (III)-                                                                             Compound                                                                            1     -1040                                                                             -1000                                                                             0   2.9                                              (A-1)                                                                              No. 24                                                                              1000  -1010                                                                             -960                                                                              -2  3.5                                       Example 38                                                                           (III)-                                                                             Compound                                                                            1     -1210                                                                             -1150                                                                             -1  2.8                                              (A-1)                                                                              No. 30                                                                              1000  -1140                                                                             -1080                                                                             -2  3.1                                       Example 39                                                                           (III)-                                                                             Compound                                                                            1     -1000                                                                             -920                                                                              0   2.1                                              (A-9)                                                                              No. 7 1000  -970                                                                              -910                                                                              -1  2.2                                       Example 40                                                                           (III)-                                                                             Compound                                                                            1     -1250                                                                             -1185                                                                             0   2.5                                              (A-9)                                                                              No. 8 1000  -1200                                                                             - 1140                                                                            -1  2.9                                       Example 41                                                                           (III)-                                                                             Compound                                                                            1     -1040                                                                             -990                                                                              0   3.2                                              (A-9)                                                                              No. 24                                                                              1000  -970                                                                              -910                                                                              0   4.2                                       Example 42                                                                           (III)-                                                                             Compound                                                                            1     -1160                                                                             -1110                                                                             -3  3.4                                              (A-9)                                                                              No. 30                                                                              1000  -1090                                                                             -1020                                                                             -5  4.5                                       Example 43                                                                           (III)-                                                                             Compound                                                                            1     -1230                                                                             -1150                                                                             0   2.0                                              (A-21)                                                                             No. 7 1000  -1200                                                                             -1110                                                                             -1  2.0                                       Example 44                                                                           (III)-                                                                             Compound                                                                            1     -1220                                                                             -1150                                                                             0   2.2                                              (A-21)                                                                             No. 8 1000  -1130                                                                             -1090                                                                             -1  2.4                                       Example 45                                                                           (III)-                                                                             Compound                                                                            1     -1210                                                                             -1160                                                                             -1  3.0                                              (A-21)                                                                             No. 24                                                                              1000  -1180                                                                             -1120                                                                             -2  3.8                                       Example 46                                                                           (III)-                                                                             Compound                                                                            1     -970                                                                              -920                                                                              -3  2.6                                              (A-21)                                                                             No. 30                                                                              1000  -940                                                                              -890                                                                              -5  3.5                                       Example 47                                                                           (III)-                                                                             Compound                                                                            1     -1030                                                                             -980                                                                              -1  2.1                                              (A-49)                                                                             No. 7 1000  -990                                                                              -910                                                                              -1  2.2                                       Example 48                                                                           (III)-                                                                             Compound                                                                            1     -1180                                                                             -1120                                                                             0   2.0                                              (A-49)                                                                             No. 8 1000  -1150                                                                             -1080                                                                             0   2.6                                       Example 49                                                                           (III)-                                                                             Compound                                                                            1     -1120                                                                             -1085                                                                             - 3 3.6                                              (A-49)                                                                             No. 24                                                                              1000  -1080                                                                             -1020                                                                             -5  4.4                                       Example 50                                                                           (III)-                                                                             Compound                                                                            1     -1240                                                                             -1155                                                                             0   2.2                                              (A-49)                                                                             No. 30                                                                              1000  -1190                                                                             -1080                                                                             -2  3.2                                       Example 51                                                                           (III)-                                                                             Compound                                                                            1     -1040                                                                             -940                                                                              0   1.9                                              (A-134)                                                                            No. 7 1000  -1030                                                                             -940                                                                              0   2.0                                       Example 52                                                                           (III)-                                                                             Compound                                                                            1     -1140                                                                             -1070                                                                             -1  2.2                                              (A-134)                                                                            No. 8 1000  -1100                                                                             -1050                                                                             -1  2.8                                       Example 53                                                                           (III)-                                                                             Compound                                                                            1     -1180                                                                             -1120                                                                             -2  3.8                                              (A-134)                                                                            No. 24                                                                              1000  -1110                                                                             -1040                                                                             -5  4.3                                       Example 54                                                                           (III)-                                                                             Compound                                                                            1     -1210                                                                             -1130                                                                             0   2.9                                              (A-134)                                                                            No. 30                                                                              1000  -1150                                                                             -1020                                                                             -1  3.6                                       Example 55                                                                           (IV)-                                                                              Compound                                                                            1     -995                                                                              -960                                                                              0   1.8                                              (A-1)                                                                              No. 7 1000  -1010                                                                             -970                                                                              0   1.9                                       Example 56                                                                           (IV)-                                                                              Compound                                                                            1     -1065                                                                             -990                                                                              0   2.1                                              (A-1)                                                                              No. 8 1000  -1020                                                                             -960                                                                              0   2.9                                       Example 57                                                                           (IV)-                                                                              Compound                                                                            1     -1210                                                                             -1130                                                                             -1  2.8                                              (A-1)                                                                              No. 24                                                                              1000  -1220                                                                             -1120                                                                             -2  3.6                                       Example 58                                                                           (IV)-                                                                              Compound                                                                            1     -1190                                                                             -1120                                                                             -2  3.0                                              (A-1)                                                                              No. 30                                                                              1000  -1120                                                                             -1070                                                                             -5  3.8                                       Example 59                                                                           (IV)-                                                                              Compound                                                                            1     -1020                                                                             -975                                                                              -1  1.9                                              (A-9)                                                                              No. 7 1000  -1000                                                                             -970                                                                              -1  1.9                                       Example 60                                                                           (IV)-                                                                              Compound                                                                            1     -1230                                                                             -1150                                                                             -1  2.8                                              (A-9)                                                                              No. 8 1000  -1220                                                                             -1130                                                                             -1  3.1                                       Example 61                                                                           (IV)-                                                                              Compound                                                                            1     -1180                                                                             -1165                                                                             0   2.0                                              (A-9)                                                                              No. 24                                                                              1000  -1170                                                                             -1150                                                                             0   2.4                                       Example 62                                                                           (IV)-                                                                              Compound                                                                            1     -1090                                                                             -1065                                                                             -1  3.6                                              (A-9)                                                                              No. 30                                                                              1000  -1060                                                                             -1030                                                                             -3  4.8                                       Example 63                                                                           (IV)-                                                                              Compound                                                                            1     -980                                                                              -965                                                                              0   2.4                                              (A-21)                                                                             No. 7 1000  -970                                                                              -950                                                                              -1  2.6                                       Example 64                                                                           (IV)-                                                                              Compound                                                                            1     -1100                                                                             -1040                                                                             0   2.0                                              (A-21)                                                                             No. 8 1000  -1050                                                                             -980                                                                              -1  2.4                                       Example 65                                                                           (IV)-                                                                              Compound                                                                            1     -1220                                                                             -1150                                                                             -2  2.8                                              (A-21)                                                                             No. 24                                                                              1000  -1180                                                                             -1120                                                                             -5  3.9                                       Example 66                                                                           (IV)-                                                                              Compound                                                                            1     -1090                                                                             -1020                                                                             -3  3.2                                              (A-21)                                                                             No. 30                                                                              1000  -1010                                                                             -920                                                                              -5  4.2                                       Example 67                                                                           (IV)-                                                                              Compound                                                                            1     -1170                                                                             -1140                                                                             -1  1.7                                              (A-49)                                                                             No. 7 1000  -1080                                                                             -1030                                                                             -1  1.8                                       Example 68                                                                           (IV)-                                                                              Compound                                                                            1     -1210                                                                             -1150                                                                             0   2.2                                              (A-49)                                                                             No. 8 1000  -1190                                                                             -1130                                                                             -1  2.6                                       Example 69                                                                           (IV)-                                                                              Compound                                                                            1     -1200                                                                             -1165                                                                             0   2.9                                              (A-49)                                                                             No. 24                                                                              1000  -1170                                                                             -1125                                                                             0   3.3                                       Example 70                                                                           (IV)-                                                                              Compound                                                                            1     -990                                                                              -955                                                                              -1  3.6                                              (A-49)                                                                             No. 30                                                                              1000  -950                                                                              -930                                                                              -3  4.8                                       Example 71                                                                           (IV)-                                                                              Compound                                                                            1     -1170                                                                             -1050                                                                             0   1.4                                              (A-53                                                                              No. 7 1000  -1200                                                                             -1040                                                                             0   1.4                                       Example 72                                                                           (IV)-                                                                              Compound                                                                            1     -1150                                                                             -1100                                                                             0   1.8                                              (A-53)                                                                             No. 8 1000  -1095                                                                             -1050                                                                             0   2.2                                       Example 73                                                                           (IV)-                                                                              Compound                                                                            1     -980                                                                              -950                                                                              -2  2.8                                              (A-53)                                                                             No. 24                                                                              1000  -900                                                                              -880                                                                              -3  3.2                                       Example 74                                                                           (IV)-                                                                              Compound                                                                            1     -1020                                                                             -990                                                                              0   2.0                                              (A-53)                                                                             No. 30                                                                              1000  -940                                                                              -890                                                                              -2  3.2                                       Example 75                                                                           (IV)-                                                                              Compound                                                                            1     - 1040                                                                            -970                                                                              -1  1.0                                              (A-66)                                                                             No. 7 1000  -1050                                                                             -970                                                                              -1  1.0                                       Example 76                                                                           (IV)-                                                                              Compound                                                                            1     -1180                                                                             -1110                                                                             -3  3.8                                              (A-66)                                                                             No. 8 1000  -1120                                                                             -1070                                                                             -5  4.2                                       Example 77                                                                           (IV)-                                                                              Compound                                                                            1     -1240                                                                             -1180                                                                             0   2.7                                              (A-66)                                                                             No. 24                                                                              1000  -1170                                                                             -1085                                                                             -2  3.5                                       Example 78                                                                           (IV)-                                                                              Compound                                                                            1     -1040                                                                             -980                                                                              -1  3.7                                              (A-66)                                                                             No. 30                                                                              1000  -975                                                                              -920                                                                              -1  4.2                                       Example 79                                                                           (IV)-                                                                              Compound                                                                            1     -1100                                                                             -1020                                                                             -1  2.1                                              (A-122)                                                                            No. 7 1000  -1050                                                                             -1000                                                                             -1  2.1                                       Example 80                                                                           (IV)-                                                                              Compound                                                                            1     -1210                                                                             -1160                                                                             -1  2.6                                              (A-122)                                                                            No. 8 1000  -1145                                                                             -1080                                                                             -2  2.9                                       Example 81                                                                           (IV)-                                                                              Compound                                                                            1     -1120                                                                             -1080                                                                             0   3.3                                              (A-122)                                                                            No. 24                                                                              1000  -1070                                                                             -1010                                                                             -3  3.7                                       Example 82                                                                           (IV)-                                                                              Compound                                                                            1     -1020                                                                             -970                                                                              -1  2.5                                              (A-122)                                                                            No. 30                                                                              1000  -950                                                                              -910                                                                              -1  3.4                                       Example 83                                                                           (IV)-                                                                              Compound                                                                            1     -890                                                                              -800                                                                              -1  0.8                                              (A-153)                                                                            No. 7 1000  -900                                                                              -800                                                                              -1  0.8                                       Example 84                                                                           (IV)-                                                                              Compound                                                                            1     -1120                                                                             -1010                                                                             0   0.9                                              (A-153)                                                                            No. 8 1000  -1100                                                                             -1000                                                                             0   0.9                                       Example 85                                                                           (IV)-                                                                              Compound                                                                            1     -1220                                                                             -1170                                                                             0   1.1                                              (A-154)                                                                            No. 7 1000  -1190                                                                             -1090                                                                             -1  1.2                                       Example 86                                                                           (IV)-                                                                              Compound                                                                            1     -1030                                                                             -960                                                                              -1  1.1                                              (A-154)                                                                            No. 8 1000  -1050                                                                             -970                                                                              -1  1.1                                       Example 87                                                                           (IV)-                                                                              Compound                                                                            1     -1110                                                                             -1010                                                                             0   1.2                                              (A-155)                                                                            No. 7 1000  -1100                                                                             -1000                                                                             -1  1.2                                       Example 88                                                                           (IV)-                                                                              Compound                                                                            1     -990                                                                              -900                                                                              -1  1.1                                              (A-155)                                                                            No. 8 1000  -980                                                                              -870                                                                              -1  1.1                                       Example 89                                                                           (IV)-                                                                              Compound                                                                            1     -1170                                                                             -1050                                                                             0   1.5                                              (A-59)                                                                             No. 7 1000  -1150                                                                             -1010                                                                             -1  1.6                                       Example 90                                                                           (IV)-                                                                              Compound                                                                            1     -940                                                                              -890                                                                              0   1.3                                              (A-59)                                                                             No. 8 1000  -950                                                                              -890                                                                              0   1.4                                       Comp. Ex. 1                                                                          CG-3 CT-1  1     -1040                                                                             -950                                                                              -5  5.6                                                         1000  -975                                                                              -890                                                                              -17 16.2                                      __________________________________________________________________________

EXAMPLES 91 TO 99

The photoreceptors of the present invention prepared in Examples 1, 15,16, 35, 36, 55, 56, 83 and 84 were used in a commercially availableelectrophotographic copier, and copying operation was then made. Inconsequence, it was found that these photoreceptors could providefog-free clear images which were faithful to an original even on the tenthousandth sheet of the copies.

What is claimed is:
 1. An electrophotographic photoreceptor comprisingan electrically conductive base and a photosensitive layer thereoncontaining a charge-generating material and a charge-transportingmaterial wherein said charge-transporting material comprises atetraphenylthiophene of the formula ##STR85## wherein AM is a tertiaryamino group and each of l, m and n is the integer 0 or 1 and l≧m≧n. 2.An electrophotographic photoreceptor as claimed in claim 1, wherein thetetraphenylthiophene AM is of the formula --NR₁ R₂ in which each of R₁and R₂ is a phenyl groupor a naphthyl group which is unsubstituted orsubstituted by at least one of a halogen atom, alkyl of 1 to 8 carbonatoms, alkoxy of 1 to 5 carbon atoms, a carboxylate group of 1 to 6carbon atoms, an aralkyl group of 7 to 10 carbon atoms, a phenyl groupand a naphthyl group.
 3. An electrophotographic photoreceptor a sclaimed in claim 2, wherein each of R₁ and R₂ is phenyl, benzyl,naphthyl or phenyl substituted by halogen, lower alkyl, lower alkoxy, orcarbo-lower alkoxy.
 4. A photoreceptor as claimed in claim 1, whereineach of l, m and n are
 0. 5. A photoreceptor as claimed in claim 1,where l is 1 and m and n or
 0. 6. A photoreceptor as claimed in claim 1,wherein l and m are 1, and n is
 0. 7. A photorecptor as claimed in claim1, wherein l, m and n are
 1. 8. An electrophotographic photoreceptor asclaimed in claim 1 wherein the photosensitive layer comprises twolayers, one of which contains a charge-generating material and the otherof which contains a charge-transporting material.
 9. Anelectrophotographic photoreceptor as claimed in claim 1 wherein thethickness of the charge-generating layer is 0.05 to 2 μm and thethickness of the charge-transporting-transporting layer is 5 to 30 μm.10. An electrophotographic photoreceptor as claimed in claim 1 whereinthe charge-generating material is an azo compound or phthalocyanine. 11.An electrophotographic photoreceptor as claimed in claim 1 wherein saidcharge-generating material is an azo compound represented by the generalformula (II), (III) or (IV) ##STR86## wherein A in formulae (II), (III)and (IV) is a coupler residuum.
 12. An electrophotographic photoreceptoras claimed in claim 1 wherein the charge-generating material is acompound of the formula ##STR87## wherein A is a group having theformula ##STR88##
 13. An electrophotographic photoreceptor as claimed inclaim 1 wherein the charge-generating material is a compound of theformula ##STR89## wherein B is a group having the formula ##STR90##